Hello,
I just wanted to add that I too have had a similar problem with my Sporty. Not to long ago on a cold morning, I started up my truck to let it get warm inside. Then I headed off to work. As I was going down the highway at about 60mph, my truck shifted itself into 4 LOW. At the time I had no idea it did this, because my dash gave no indication that I was in 4 LOW. I had though that my transmission went on me. It happened all of a sudden as my rpm's shot up and my truck started to scream. Naturally I slowed down. I was able to drive home at no faster than 30mph. After some troubleshooting once I got it home I noticed that when I tried to use the switch to shift into 4 wheel drive, the shift was not working at all....As in it was not shifting into 4wd and it had no light indicators. I pulled the fuse on it put it back in and still no luck. Disconnected the battery and again, no luck. Finally I removed to 4x4 module, inspected it...nothing seemed wrong with it...stared at it a bit...and put it back in. Once I started the truck up....viola!...My dash was now indicating that I was in 4 LOW, and I could switch it back to 2wd...which I did. To prevent this problem from happening again I disconnected the 4x4 module until I had time to figure out exactly what was wrong.
So, from reading through the posts on this website I found that it could be...
1. The 4x4 module (4x4cm)
2. The Transfer motor.
3. Bad connections to the transfer motor.
4. The Switch itself (I don't think it is a switch issue)
From what I have read on here is that when people replace their 4x4 module sometimes the problem remains. I also read either here or somewhere else that when someone had a problem with the 4x4 module that the guy at the yard said usually people replace the transfer motor rather than the module. So, today I am going to look at the connections to the transfer motor and clean them pretty good. My transfer motor does look pretty junky, however most of my underbody is rusted anyway so it is not surprising that it looked that way.
Hope this offers some insight...I'm still working on the problem and am torn between replacing the transfer motor or the module. The motor can be had for $80. I am afraid to buy a module because to get it on the cheap is to buy it used, and I may just be buying somebody's junk. Like if my module was bad and I bought a replacement and then sold mine on EBAY...lol.
Neal